Reuseable plug fuse



May 19, 1953 o. c. LARsoN, SR 2,639,351

REUSEABLE PLUG FUSE Filed May 17, 1951 WWW 11% INVENTOR OTTO c. QRsoN/SR v BY ATTORY Patented May 19, 1953 UNITED STATES PATENTr OFFICE REUSEABLE PLUG FUSE 1 Otto Larson, Sr., Brooklyn, N. Y.

Application May 17, 1951, Serial No. 226,786

This invention relates to fuses and, particularly, to the more or less conventional screw-in type of fuse. More particularly, the invention deals with fuses of the kind under consideration having means, whereby parts of the fuse may be removed and the burned out fuse element replaced, so as to provide indenite use of the main body portion of the'fuse.

The novel features of the invention will be best understood from the following description, when taken together with the accompanying drawing, in which certain embodiments of the invention are disclosed and, in which, the separate parts are designated by suitable reference characters in each of the views and, in which:

Fig, l is a cross-sectional view through a more or less standard type of fuse, showing one method oi" separating the fuse body parts and novel Fig. 4 is 'a partial section on the line 4-6 ofy Fig. 3; and

Fig. 5 is a view similar to Figli showing another form of construction.

With fuses of the type and kind under consideration, it has been customary to employ a fused plug body with a positive and xed arrangement of fuse element therein so that, when the fuse has blown, the entire fuse was disposed 0i. It is the purpose of my invention to modify and construct devices of the kind under considera-tion in such manner that the fuse element itself, when burned out or blown. can be replaced simply byy another element at an extremely nominal cost, thus 'extending to the body structure of the fuse, .as a

whole, a long, useful life.

In Fig. l of the drawing, I have shown what may be termed a standard or conventional type of fuse body, comprising a hollow plastic or other insulation base IU having a downwardly extending conical terminal end I I, with Aa center terminal I2 exposed at the outer surface thereof.v The body I0 has an outwardly projecting annular flange I3. At I4 is shown a thimble-Snaped calf). usually composed of glass, the peripheral walls of the cap i4 being threaded, as indicated at l5, to receive the threaded metallic shell I6, having an inturned, lower end I1, which seats upon the ange vand which draws the cap I4 firmly onto 5 Claims. (Cl. 20G-130) One wall of the cap I4 has a longitudinal groove or keyway I8 therein and slidably mounted in this groove or keyway is a removable key bar I9 which I employ for detachably coupling the parts for removal of a fuse element 20, mounted as later described. The key bar I9 has an outer grooved surface 2|, which is adapted to be frictionally placedl beneath the threaded portion of the sleeve I6 to hold the key bar in position and, at the same time, facilitate normal use of the plug in threading the same into and out of a fuse socket.

Arranged within the chamber 22 of the body I0 is a terminal strip 23, soldered or otherwise to the terminal I2 and the upper end of the terminal strip 23 has a spring end 2li. in which one end portion 20 of the fuse element 2Q is frictionally and tensionally supported. Another contact strip 25 is disposed on the body Iil and includes a Dortion 26 wrapped around the fiange i3 to establish contact with the sleeve Iii, as clearly illustrated in the drawing. The contact strip 25 is fixed to the body I0 by a rivet, or the like, fil and the other end 2D of the fuse element 2B is adapted to be 'Y placed between the upper free end 28 of the contact strip 25 and the body il? and having a positive frictional engagement with the end 28. From the foregoing construction, it will be apparent that, as and when the fuse element blows or burns out, this element can be replaced by a new fuse element by simply drawing upwardly on the key bar I9, removing it from the recess it, whereupon, the capV 24 can be turned out of the sleeve I 6, the old fuse element removed and a new one placed in position. after which, the cap I4 is replaced and the key bar I9 again put into operative position.

vIn Fig. 2`of the drawing, I have shown a slight modication of the construction shown in Fig. l,

Vwherein a more or less standard fuse body is modifredto a slight extent in detachably Coupling the bodyA parts and in establishing electrical cirl'employed for completing circuit' to the terminal end 33, vsimilar to the terminal end I2. The strip 32 is bent over the upper portion of the body 29, as seenat 34, and within the chamber of the body,

5,5 thestrip 32 .has a .spring contact strip `35 fixed thereto for. engagement with one end of a fuse element 36, generally similar' to the element Eil.

The body 29, on a wall thereofvopposed to the strip 32, has another strip 3l enveloping the upper end portion thereof and this strip, together` with a spring catch and contact device 38, are fixed to the body 29 by a rivet, or otherwise, as at 39. The upper end of the catch and contact 38 has an end 40, similar to the end 28 for engagement with the other end of the fuse elementt. The lower end portion of the catch and Contact t8 has an ois'et catch element 4I adapted to engage the inturned lower portion 42 of the shell 3l, the catch 33 Operating in a slot in this inturned portion vandis shown in the locked position in Fig. 2. By pressing inwardly on the lower iingerpiece end 43 of the catch 38, the body 29 will be released for displacement frorn the cap (ill and shell 3 I.

It will also appear that the iingerpiece Aend t3 of the catch and contact 3d operates in a recess 451m the ange `portion 'of the body 29 and protrudes suiiiciently 'beyond 'this `flange portion to vvbe engaged by va tool or the viingernail of 'a hand. v'Ihe catch 3i; also establishes the electrical connection oi one end of the fuse element 36 with the shell, 'as 'will be apparent. However, the catch will not interfere with vthe rotation of the fuse in screwing the'saine into and VYout of' a lu'se socket.

In Figs. 3' and "4 ofthe drawing, I have shown a novel type 'or plug fuse, wherein va unitary plug body assemblage 45 is employed, comprising a solid core f46 of insulating materialfand an outer fsleeve 4l 'of similar material, 'the sleeve having,

on its upper surface, projecting segments 4l,

vhaving undercut grooves 48 on opposed parallel edges for reception of a transparent slide or strip 49 which, vin the constructionshown, is illustratedas a iflat strip, but Athis member can be -oi'any desired cross-'sectional form. The strip 49 has airi'ctional 'engagement with the body '4l yand is contain'edwithin boundaries of the body, 7'asls'e'en in Fig. 3, but can be forcibly 'removed whenever desired.

Actually, the rbody y45 is inthe form of a screwin socket, with which conventional plugs are coupled for completing circuits'to electrical appliancesand this body has been modified to convert the `same to'a fuse by simply interposing'a fuse v`element t between the spring contact portions 5I and t52 in the manner vclearly seen in Fig. 4 ofthe drawing. Normally, these contact portions 'would receive thef'spaced terminals of the conrve'ntional plug. As indicated in Fig. 2, the spring contact portion 5I is in circuit with the threaded AshellFu'i of said body. It will th-us be apparent that, by the slight. conversion or modication in `the' structure 'of the body, the same is converted into a practical fuse, wherein the fuse element 523 can lbe replaced, when blown, by simply removing the slide or strip 49, substituting the new fuse velement and then replacing the slide 49 for a continued use-of the fuse.

InF-ig. 5 of the drawing, Ir have shown another form of construction, wherein a more or less `standard type of socket 45 is shown, that is to say, `a socket generally similar to the socket l45, such as areemployed in connection with plugs having spaced terminals to complete electrical circuit with spring contacts 5I :and 52 of the socket body 45. In Fig. 5, a fuse element 5H', similarv to the fuse 5t, isbridged across theterminals yor spring contacts`5I,.-52'Land thesecontacts fare held in firm engagement" with `the ends 4 of the fuse clement by the spaced posts or bars 55, 56 of the plug-like body 5T. The body 51 is modied to the extent that the outer end of the bore 58 thereof has a recess 59 in which a suitable transparency 60 is xed, this transparency giving visibility to the fuse element 50. With the device, as shown in Fig. 5, it will be understood that, when the fuse element 50 blows or burns out, the socket body 45' is removed from lthefuse socket, after which the plug-like body 5l is vpulled out of the body 45', whereupon the burned out fuse element can be removed and a new fuse element 50 placed in position, after which the body 5l is replaced and inward movement of the bars 55, 56 will securely and firmly *establish 'engagement of the contacts 5 I 52' with theendsofethe fuse element 5t'.

It will be apparent that, with the several forms of construction shown, the fuse elements cornprise a fuse strip having, at the center portion thereof, .the desired control, from a rstandpoint 'of Vamperage from the. lowest to the highest amperage usually kprovided in plugs of this type and kindandtotherwise thesefuse elements have the vintu'rned contact ends for establishing engagement'wth the vdifferent contacts disclosed. The body .portion of the fuse plugs can be suitably marked to design-ate the amperage of the 'fuse and, with structures of the kind under consideration, in the sale of one `fuse body, a number of fuse `elementsI can be sold with the body for -replacement or removal whenever desired and, to avoid vconfusion in this regard, each fuse element 'can be stamped to identifyampe'rage thereof. This will be beneficial in theindividual sale of the elements for .replacement of old and burned out elements.

`1n considering Fig. 1 of the drawing, it will be apparent that partof the threaded portion'of the shell I6 is cut-out to receive the Vkey har I9, which 'keys the shell against rotation. It 'will Aalso appear that the fuse element has a central amperage control portion and short substantially parallel terminal ends.

Having fully described my invention, what I claim as `new 'and desire to secure by Letters Patent is:

l. A fuse of the rclass described, comprising two detachably coupled body parts of insulating material arranged one upon the other, one of said vparts having a terminal at the outer end thereof, a threaded sleeve forming the other terminal, said sleeve being in -eingagr-rn'ient with the other of' said partsand engaging the first part to form an assemblage or Vsaid parts, spaced spring contacts ywithin said parts, one contact vbeing in Vcircuit with'said endterminal, the other contact being in 'circuit 'with saidsleeve terminal, a fuse element detachable with and bridging and electrical-ly connecting said spring contacts, and means movable on and keyed to oneof said parts to render the Vfuse element accessible for replacement.

r.2.A fuse of Athe class described, `comprising two detachably coupled body parts of insulating material arranged Vone 'upon the other, one of said parts having a terminal at the outer end thereof, a threaded sleeve forming the other terminal, said sleeve being in engagement with the other 4of said parts fand'iengaging the'flrst part to form an vass'embla'ge of said partsfspaced spring contacts within vsaid ;pa1ts,;onecontact being incircuitwithf-Said 'end "terminal, 'the other "contact element detachable with and bridging and electrically connecting said spring contacts, means movable on and keyed to one of said parts to render the fuse element accessible for replacement, and said means comprising a bar keyed to and slidable on the second named part and engaging said sleeve to ret-ain the sleeve against rotation on said body part.

3. A fuse of the class described, comprising two detachably coupled body parts of insulating material arranged one upon the other, one of said parts having a terminal at the outer end thereof, a threaded sleeve forming the other terminal, said sleeve being in engagement with the other of said parts and engaging the first part to form an assemblage of said parts, spaced spring contacts Within said parts, one contact being in circuit With said end terminal, the other contact being in circuit With said sleeve terminal, a fuse element detachable With and bridging and elec-- trically' connecting said spring contacts, means movable on and keyed to one of said parts to render the fuse element accessible for replacement, and said means comprising a spring catch and contact exposed through both of said body parts and engaging said sleeve to establish electric circuit With the sleeve and to retain the body parts against relative movement.

4. A fuse device of the class described, comprising a body of insulating material, said device having a terminal at one 'end and an external threaded sleeve forming the other terminal, spaced spring contacts within said body, one contact being in circuit with said terminal end, the other contact being in circuit with said sleeve terminal, a fuse element detachable with and bridging said contacts to complete an electric circuit therebetween, means retaining the fuse element in contact with said terminals, and means comprising a member movable relatively to and keyed to the body part for rendering the fuse element accessible for replacement.

5. A fuse device of the class described, comprising a body of insulating material, said device having a terminal at one end and an external threaded sleeve forming the other terminal. spaced spring contacts Within said body, one contact being in circuit With said terminal end, the other Contact being in circuit with said sleeve terminal, a fuse element detachable with and bridging said contacts to complete an electric circuit therebetween, means retaining the fuse element in contact with said terminals, means comprising a member movable relatively to and keyed to the body part for rendering the fuse element accessible for replacement, and said member comprising a bar keyed to said threaded sleeve to prevent rotation of the sleeve on said body part.

OTTO C. LARSON, SR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,847,970 Mertz Mar. 1, 1932 2,170,168 Vanderveer Aug. 22, 1939 2,420,837 OConnor May 20, 1947 

